Dissertation committee:
Αθανάσιος Τσακρής, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Χαράλαμπος Μπιλλίνης, Καθηγητής, Τμήμα Κτηνιατρικής, Πανεπιστήμιο Θεσσαλίας
Ιωσήφ Παπαπαπαρασκευάς, Αναπ. Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Γεωργία Βρυώνη, Αναπ. Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Βασιλική Σπύρου, Καθηγήτρια, Γενικό Τμήμα, Πανεπιστήμιο Θεσσαλίας
Γεώργιος Παναγιωτακόπουλος, Επικ. Καθηγητής, Τμήμα Ιατρικής, Πανεπιστήμο Πατρών
Πολυχρόνης Κωστούλας, Επίκ. Καθηγητής, Τμήμα Κτηνιατρικής, Πανεπιστήμιο Θεσσαλίας
Summary:
The present dissertation focused on the molecular investigation of common pet fleas for pathogenic bacteria and the assessment of the IgG antibody vector in the population against Rickettsia typhi, Bartonella henselae and B. quintana, in the area of Attica, Greece.
The flea samples from animals were collected from veterinary clinics and the human samples from private microbiological laboratories. Conventional and real-time PCR and next-generation sequencing of the 16S rDNA gene were used for the molecular investigation of fleas. Serological tests were performed by indirect immunofluorescence test (Vircell ™, Santa Fé, Spain), according to the manufacturer's instructions. The characterization of bacteria with potential health significance was based on the International Statistical Classification of Diseases and Related Health Problems by WHO (ICD-11, 2019 version).
Of the flea samples, 100 consisting of only female fleas were selected for analysis, which included 96 samples with Ctenocephalides felis, 2 samples with Ctenocephalides canis and 2 samples with Pulex irritans, collected from 67 cats and 33 dogs.
Rickettsia genus was confirmed in 16 specimens of which 14 were confirmed for R. felis; eight belonged to cats and six to dogs.
Bartonella spp. was detected in 32 samples. Of these, species was determined in 27: B. clarridgeiae in 12, B. henselae in seven, B. koehlerae in one, while the remaining seven had a mixed infection with more than one Bartonella species. All positive samples came from cats except from one in which the species was not identified.
The sensitivity of the molecular methods for the genus Rickettsia ranged from 62.5% to 93.8% and the specificity from 65.0% to 100%. R. felis-specific molecular tests showed 92.9% to 100% sensitivity while specificity ranged from 65.0% to 100%.
Bacterial genera with potential health importance in the flea microbiome were: Acinetobacter, Actinomyces, Bacillus, Bacteroides, Bartonella, Bifidobacterium, Brucella, Campylobacter, Clostridium, Corynebacterium, Coxiella, Haemophilus, Enterococcus, Legocellus, Enterococcus, Moraxella, Morganella, Mycobacterium, Neisseria, Nocardia, Pasteurella, Propionibacterium, Proteus, Pseudomonas, Rickettsia, Salmonella, Serratia, Staphylococcus, Stenotrophomonas and Streptococcus. The distribution of these genera did not differ between cats and dogs except in Bartonella spp. which was most frequently found in cat fleas (OR = 27.6, p <0.001). The genera Coxiella, Campylobacter, Legionella, Spirochaeta, Salmonella, Brucella were found only in cats however without statistical significance. The bacterial species of health importance were 40 and included Acinetobacter baumannii, Bacteroides fragilis, Clostridium perfringens, Enterococcus faecalis, E. mundtii, Fusobacterium nucleatum, Haemophilus aegyptius, Kingella kingae, Klebsiella Leneum, Klebsiella leneum Pasteurella multocida, Propionibacterium acnes, P. propionicum, Proteus mirabilis, Pseudomonas aeruginosa, Rickettsia australis, R. hoogstraalii, Salmonella enterica, and various species of Bartonella, Staphylococcus and Streptococcus.
IgG antibodies for B. henselae were detected in 14.3% and for R. typhi in 1.0% while IgG for both pathogens in 3.5% of participants (N = 202). A positive correlation of seropositivity for IgG for B. henselae with residency in sea port area was found (X2 (6) = 17,737, p = 0.009).
According to the findings of the dissertation a significant percentage of the pet fleas in Attica carry pathogenic bacteria, whereas cat fleas are more often infected with Bartonella. The great variety of bacteria of health importance in fleas and the complex interface of contact of these insects with humans, necessitate a more extensive investigation on the flea pathogen potential. A percentage of the population of Attica has exposure to Bartonella and Rickettsia while especially for the Bartonella bacterium the probability of exposure appears increased in the area of the largest commercial / passenger port of the country. Epidemiological surveillance and laboratory diagnostic capacity for Rickettsia and Bartonella infections should be strengthened. Special attention should be paid to the adverse impact to the cardiovascular health of the population caused in the long run by the Bartonella bacterium.
